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Application of Palynology in Taxonom and Phylogeny - the case of Pollen Morphology of the Genus Iris L. (Iridaceae) from the Southern European Area

On the territory of Southern Europe the genus Iris is represented by Alpine-Dinaric, Mediterranean and Pannonian taxa, from the subgenera Iris and Limniris. Impressive variability of both subgenera caused a lot of taxonomical confusions. Systematic relationships of some critical Iris groups from the area have been suggested earlier, based on the results of morphological, anatomical, karyological and molecular analyses. However, only a few palynological data about them are known. Therefore the aim of this study was to research pollen morphology of Iris taxa from the southern European area and to investigate its potential taxonomical and phylogenetic significance. We have studied pollen morphology of about 30 taxa, represented by two or more populations. Pollen samples were obtained from the field or from the Iris-collections of Botanical gardens and several collections from private gardens. Pollen grains were analyzed in both hydrated and dry conditions by using a scanning electron microscope. All pollen grains are sulcate with a few palynological features which could have taxonomical importance on different classification levels: shape of dry pollen grains ; shape, outline and approximate size of hydrated pollen grains, approximate size of the sulcus, ornamentation of the sulcus membrane and of the exine. At least four pollen types were recognised and taxonomically delimited to the series level: two of them characterize the subgenus Iris, section Iris (series Elatae and Pumilae) and two the subgenus Limniris, section Limniris (series Laevigatae, Sibiricae and Spuriae). Taxonomic implications of pollen morphology of their critical groups and taxa have been evaluated. Possible phylogenetic implications of pollen morphology of the genus Iris on the Southern European area were suggested: the subgenus Iris is more advanced than the subgenus Limniris ; I. graminea seems to be the most primitive member of the subgenus Limniris on the Southern European territory ; pollen morphology of the population of the subspecies I. sibirica subsp. erirrhiza from the Mountain Bjelolasica could represent a link between the subgenera Limniris and Iris on the territory of Southern Europe. The possible pathway of evolution of the genus Iris on the territory of Southern Europe was suggested: from the subgenus Limniris, through the “linked taxon” I. sibirica subsp. erirrhiza from the Bjelolasica Mountain (Croatia), to the subgenus Iris, series Pumilae and finally to the series Elatae. To conclude, the data on pollen morphology obtained in our work could provide helpful insight into taxonomic and evolutionary trends at the subgeneric and infrasubgeneric levels of the genus Iris on the territory of Southern Europe. Moreover, these data are in accordance with several molecular phylogenetic studies of the Genus Iris.

Iris; Iridaceae; Southern European Area

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